Upper Devonian trilobite diversity
The Frasnian trilobite fauna is markedly different
from that of the Givetian. Members of Acastidae are dominant, sometimes being alternated
with Scutelluidae and rare Aulacopleuridae and Proetidae, mostly dependant on particular
facies types. Especially the acastid Bradocryphaeus can locally be abundant in the
shales of the Moulin Liénaux Formation. Scutelluid species occur mostly in bioherms.
The
Famennian in the Ardennes is characterised by environments that were unfavourable
to trilobites. Very little is known about the trilobite fauna of this period although
there are occasional accounts of phacopids.
A pygidium of Heliopyge helios from the Moulin Liénaux Formation in Nismes (near the type locality).
A cephalon of Bradocryphaeus vanherlei from the Moulin Liénaux Formation in Nismes.
